Michael Hamilton joins a traning course
for the revolutionary new Buddy Inspiration rebreather in Hurghada
in the Red Sea.

I was mesmerised by the cloud of glassfish that
hung around me, clung to me really, in a gently pulsating mass.
At the same time I was inwardly celebrating my total lack of decompression
obligations – even though I had already spent the best part
of an hour on a Red Sea wreck at 25m.

A totally silent interaction with nature and an hour’s bottom
time at 25m, breathing a moist Nitrox mixture – this is the
diving of the future. It’s not scuba, it’s ccuba: closed
circuit underwater breathing apparatus.

More than half a century after Cousteau first opened a window on
the underwater world for recreational divers, it is only now, with
rebreathers, that the magical realm he famously dubbed The Silent
World is beginning to live up to that name.

Anyone who has dived with open-circuit scuba knows how noisy it
is listening to the sound of your own breathing.

I was testing the new Buddy Inspiration rebreather from UK manufacturer
AP Valves, in Hurghada, Egypt. On one hand, it was an amazing experience.
On the other, it was like learning to dive all over again. It was
comical on day one to see a group of us, mostly advanced BSAC, TDI
and PADI instructors with thousands of dives between us, struggling
with our buoyancy and making the kinds of mistakes that our students
normally make.

Using the Inspiration is
not really that complicated. Yes, there are a few new rules to learn,
but the main problem for experienced open-circuit scuba divers is
that there are a lot of ingrained rules to unlearn.

Mastering buoyancy was the first problem. The unit weighs approximately
27kg, so if you are used to diving with aluminium 12-litre tanks
and a 5mm wetsuit in the Red Sea (as is common) you can dispense
with a lot of the lead you would normally use. I found that just
one 2kg weight in a special pocket on top of the unit stopped it
riding up in the water into a vertical position.

Most of us were grossly overweighted
until we sorted it out. On land the unit is fairly bulky, but in
the water it felt quite streamlined, especially when compared with
its closest American counterpart, the CisLunar, which weighs twice
as much.

Because you are on a closed circuit breathing loop, descending
takes a bit of practice and you can no longer use lung-volume to
control your buoyancy. You need to get air out of the wings-style
BCD, your lungs and the counterlung, or breathing bag, to descend.
Exhaling through your mouth doesn’t work; you need to exhale
through your nose.

Then, as you start to descend, you have to add air to the counterlung
by pressing an inflate button, similar to the inflate button on
a drysuit, in order to breathe.

Again, with practice, you learn how to maintain a constant volume
in the loop for ease of breathing. Repeated mask clearing –
if you have a leaky mask – effectively turns the unit into
a semi-closed rebreather (because you’re venting air into
the water periodically) so it’s essential to have a well-fitting
mask to avoid wasting your air (diluent).

The unit is mounted on
your back just like a conventional scuba unit, but you have two
3-litre cylinders, one containing oxygen, the other diluent and
a twin-hose assembly and mouthpiece like old-fashioned open-circuit
rigs. As you breathe from the loop, carbon dioxide is removed by
the scrubber unit which sits between the tanks – all housed
in a stylish, yellow plastic fairing.

Setting up the Inspiration for diving needs a little more preparation
than conventional scuba. First you need to check that the scrubber
material – sofnolime – which filters out the carbon
dioxide, is in good condition.

Next you turn on the two electronic handsets which control the
oxygen levels in the breathing mix; the first is the master, the
second is a back-up or slave. They run through a self-diagnostic
check for battery level and calibration, reminding the diver of
essential checks to make before asking: ‘Dive now?’
It’s virtually impossible to make a mistake in following the
menu of questions and instructions.

However, on the course I attended in Hurghada,
three machines out of seven went down with water in the handset electronics
(see last month’s Dive International: Sweet Inspiration: the
rebreather revolution).

Martin Parker, managing director of AP Valves, comments: ‘We
are obviously looking at the leaking handsets problem, but the important
thing is that the unit does tell you if there is a power problem.’

The main advantage of CCR is the use of a constant partial pressure
of oxygen, which means the actual percentage of oxygen in the Nitrox
mix is varying constantly with depth throughout the dive. At greater
depths oxygen toxicity is kept at bay, and at shallower depths the
mixture breathed is a progressively oxygen-rich one.